ST-Link on Nucleo crashes ("Cannot access target")

[JuM]

On my workstation ​I am facing more and more often crashes of ST-Link debug connection.

I am using Keil MDK V5.28 (also tried 5.26, V5.34a...) while running debug e.g. with Nucleo STM32G071 (same problem with Nucleo STM32F091...) debugger stops with message "Cannot access target...".

So made a new project from scratch.

With USB Analyzer was able to catch communication at such a crash.

Maybe a ST-Link professional can tell what is going wrong ?

[Brian TIDAL]

Hi,

check the VDD power supply : you may have a loose connection on the JP6 (IDD) jumper that cause VDD supply being randomly lost.

Rgds

BT